For people suffering from Orthostatic Intolerance, Postural Orthostatic Tachycardia, Mast Cell Activtation or EDS. Follow me as I document my struggle towards better health.

Chest Pain and Postural Orthostatic Tachycardia Syndrome

Have you ever wondered why people with POTS or OI get chest pain?  According to Dr. Raj in his paper The Postural Tachycardia Syndrome (POTS): Pathophysiology, Diagnosis & Management, "chest discomfort" is one of the common clinical features of the condition.

I get chest pain frequently when I am in Stages IV or V and only occasionally when I am in Stages II or III.  It can be a very frightening aspect of POTS and OI because although you may have experienced the same pain many times in the past, there can be a nagging doubt in the back of one's mind that says "OK this time it's really a heart attack"

Over the years I have asked a number of cardiologists and general practitioner MDs for an answer as to what causes the pain and I always receive the same response.  (See picture on right.)

That is until I asked two experts; our very own Dr. B. Levine and a Dr. Klabunde, Associate Professor of Physiology at Ohio University who has a cool website called cvphysiology.com which has lots of interesting and colourful pictures describing the cardiovascular system.

Why do POTS patients have chest pain?
Answer #1 from Dr. Levine
I find this a rather comforting response without being a definitive answer to the question. The response refers to the fascinating theory of "hyper-vigilance" which makes POTS patients sound like people who weep over stubbing their toe or getting splinters in their fingers....
"This is a very difficult question and I must admit that I am not certain of the answer.  I am quite confident that it is not heart pain though, at least in the vast majority of POTS patients.  I do have to be cautious however since every person is an individual and there may be unusual patients with coronary anomalies (when the coronary arteries are in the wrong place; associated with ~ 15% of deaths during sports in young people), genetic abnormalities of cholesterol metabolism (such as familial hypercholesterolemia), or even true coronary spasm (constriction of the heart arteries, either in the large or small blood vessels; this latter is also called "syndrome X" and in some women is associated with a reduced ability to increase blood flow in the microcirculation of the heart). However most POTS patients are previously healthy young women with normal coronary arteries, and ECGs, even during chest pain virtually always fail to show any changes of myocardial ischemia/injury, such as might be seen with coronary spasm. 
It is important to remember that there are lots of things in the chest other than the heart that can cause pain -- the esophagus, joints connecting the ribs to the sternum, chest muscles, lining of the lungs and heart, etc and these can be quite painful.   I think that most patients have reflux with esophageal spasm, or occasionally inflammation of the chest wall joints or structures. Most POTS patients have normal heart function on echocardiograms (all in my experience) and therefore no evidence that the heart is being injured or damaged. 
The Mayo clinic group have written about the "hypervigilance" associated with POTS and I believe this plays some role too.  Let me emphasize that this does not mean the patients are making it up -- rather that sensations that fail to rise to our awareness in most individuals, seem to be more acutely sensed by POTS patients.  To keep in line with our model, as a counterpoint to the "runners high" (associated with endorphin release and downregulation of endorphin receptors), we jokingly refer to this problem as the "couch potatoe's low" (reduced endorphin levels and dowregulation of receptors) and first noticed the phenomenon in our bed rest studies.  Procedures like pulling off of electrodes, or putting in IVs which were almost painless before bed rest, became nearly intolerable after bed rest, with one volunteer literally jumping off the bed after a blood draw."

Answer #2 from Dr. Klabunde
The Klabunde answer has an interesting theory but please also read Dr. Levine's reply following this answer.
"Chest pain can occur in patients with tachycardia because increased heart rate increases myocardial oxygen demand (seehttp://www.cvphysiology.com/CAD/CAD004.htm). Furthermore, increased heart rate reduces the length of diastole (cardiac relaxation and filling) relative to the length of systole (cardiac contraction and ejection). Because most of the coronary blood flow occurs during diastole (see http://www.cvphysiology.com/Blood%20Flow/BF001.htm), tachycardia can impair coronary blood flow and therefore oxygen delivery. The bottom-line is that tachycardia can reduce the oxygen supply-demand ratio (see http://www.cvphysiology.com/CAD/CAD006.htm).  This leads to myocardia hypoxia and anginal symptoms in some patients, particularly those who already have underlying coronary or heart disease."
Response from Dr. Levine to Dr. Klabunde's answer:
"POTS patients have normal coronary arteries and young, healthy people often get very high heart rates during periods of increased myocardial oxygen demand, LIKE DURING EXERCISE! This does not cause angina. In my opinion, as both a cardiovascular physiologist and clinical cardiologist, the chances of this pain being due to the heart's being starved of oxygen is virtually zero."
Creepy Heart Cartoon
So although many people with POTS and OI experience chest pain or discomfort, there could be variety of explanations as to why.  However, I believe that the two answers above serve to highlight the importance of a full diagnostic work up to rule out other possible conditions that may be causing POTS and OI symptoms such as chest pain.

They also serve to remind me that I prefer NOT to encourage any other conditions like heart disease to be troublesome along with POTS and OI...hooray for carrots (and other vegetables)